Centrifugal switching device.



s. L. ARMSTRONG.

CENTRIFUGAL SWITCHING DEVICE. APPLICATION FILED JUNE 14, m2.

' 1,150 0, v Patented Aug. 17, 1915;

- Q I mvsmua 7 manual posed'that it 'hasbeen subjected to excessive" According tomy present invention, '1 pro- UNITED STATES PATENT OFFICE.

STANLEY L. ARMSTRONG, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR T WESTING- HOUSE ELECTRIG AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

I CENTRIFUGAL SWITCHING DEVICE.

Patented Aug. 1'7, 1915.

Application filed June 14, 1912. Serial No. 703,677.

resident. of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Centrifugal Switching Devices, of which the following is a specification.

My invention relates to centrifugal switching devicesand it has special refer- .ence to speed-limit devices such'as are employed in'connectionwith rotary converters and other dynamo-electric machinesfor the I" purpose of preventing excessive speeds.

One'of the. objects of my invention is to provide a device of the above-lndlcated characterthat shall be simple and durable in construction, effective and reliable in operation, and be so constructed as to operate .With uniformity and positiveness.

In the prior art, it has been customary to .employ devices of this general characfter for similar purposes,-but-such devices have usually been constructed .and operated in substantially the manner. ofengme shaft governors which are particularly adapted for speedregulation and in which the centrifugally actuated weighted member is moved slowly to its. outward position, in accordance with the increase of speed. Hence, the switching devices which are ada ted to be actuated by the weighted mem ers, have been subjected to a series. of light blows prior to the time'when' the weighted trip; ping member reaches its full outer position,

and the operation thereof hasthereforebeen "Furtherunreliable and unsatisfactory. 7 more, the spring which is usually employed for, restraining the centrifugally actuated member in its inner position'has been so disdistortions during the operation of the device, whereby a certainamount of set has been produced therein which has resulted in.

non-uniformity ofoperation.

' vide a, speedflimit device embodying a tension spring that is attached substantially at the middle of the central member of' the mechanism and is disposed substantially parallel to the outer link member. Thus,

the spring acts upon the linkage in a direction substantially at right angles to the direction of movement of that portion of the linkage to which it is attached and, by reason of this peculiar construction and arrangement of parts, the elongation. of the spring is reduced to a minimum. Furthermore, the construction of the device is such that, when a predetermined speed is attained, the torque on the weighted member produced by centrifugal force predominates over that eflected by the spring and, consequently, said member is moved outwardly into its outer position. The arrangement of parts and proportions thereof are so chosen .that', after the weighted member starts to move outwardly, it is caused to move the entire distance quickly, and no intermediate positions can be maintained. Thus, a positive action of the tripping device is secured and a single effective blow is delivered to the switching device, whereby its operation -is rendered definite and reliable.

My invention may best be understood by reference to the single figure of the accompanying drawing, which is a view, partially in end elevation and partially in section, of a device constructed in accordance with my invention. f-Referring to the drawing, the device here shown comprises a tripping device 1 and a switching device 2, said tripping device 1 comprising essentially a rotatable shaft 3, a pivotally mounted weighted arm 4, a second pivotally mounted arm 5, a connecting link 6, a spring-7- and a main body or supporting member-8 with which said parts are associated. I

.The switching device 2 is conveniently secured to a lug 9 which forms an integral part of a supporting bearing or pedestal 11) for the shaft 3, and said switching device comprises a casing or boxll, a plurality of stationary contact terminals 12, a cooperating movable contact member 13, an actuating spring 14, a latch 15 and a pawl or dog 16 which is adapted to be engaged and actuated by the weighted member 4 when it 00- cupiesiits outer position. v The main body member 8 is substantially v cylindrical in form, having an outwardlv projecting peripheral flange 18 that is provided with an opening 19'for the purpose of permitting unrestricted operation of the weighted arm 4, and said member 8 is suitably secured to the shaft 3. The arm 4 is body member 8 by a stud 22 and the link isv interposed between its free end and the arm 4, with respect to the link 6 an weighted end of the arm 4. The link 6 is disposed substantially at rightangles to the arm 5, and the spring 7 is attached thereto at approximately its middle oint, said spring 7 being disposed substantlally parallel to the arm 5. The other end of the spring 7 is suitably secured to a lug 23 on the bodymember 8, and said spring is normally maintained in tension, tending to restrain the weighted member 4 in its inner initial position. The tension of the spring 7 may be varied, as desired, by means of a suitable adjustable connecting device 24 that is employed between the spring and the link 6.

\Vhen the shaft 3 is at rest or is rotated at les'sthan the speed for which the trippin device 1 is adjusted to operate, theweighte arm 4 is maintained in its inner position by the spring 7 against a suitable stop 26. Inasmuch as the spring 7 is disposed substantially parallel to the arm 5, there is no component force tending to rotate said arm about its pivotal support 22. However, by reason of the relationship of the wei htgd t e spring7, said arm is acted upon by a force tending to rotate it in a counter-clockwise direction, whereby the linkage is maintained in its inner position against the stop 26.

The stationary contact terminals 12 are suitably mounted upon an insulating block 27 that is secured to the bottom of the casing or box 11 and, connected to said terminals, are conductors 28 which project through insulating bushings 29 that are provided in the back wall of the casing 11.

The movable contact member 13 is adapted to cooperate with and bridge across the I stationary contact terminals 12 and is suitably mounted upon a supporting rod 30 and insulated therefrom. The rod 30 is vertically movable in a bearing or bracket member 31 and is provided wlth a downwardly projecting extension 32 which projects through the bottom wall of the casing 11 and the end of which is provided. with a button 33. The spring 14 surrounds the rod 30 and is disposed between the bearing bracket 31 and the insulated movable contact member 13 and tends to actuate the rod 30 and its associated movable contact member 13 in a downward direction whereby said contact member is maintained in coiiperative en-' gagement with the contact terminals 12 which is normally adapted to rest upon the upper edge 36 of the movable latch 15. The

upper edge of the latch 15 is provided with a recess or depression 37 which is located immediately adjacent to that portion of the latch on which the pin 35 normally rests. A spring 38 is interposed between the latch 15 and the casing 11 and tends to maintain the latch in its extreme right-hand position. One end of the latch 15 is supported upon a stud 39 and is provided with a downwardly projecting portion 40 which serves as a stop and restricts the movement of the latch in a longitudinal direction to the right. The other end of the latch 15 is pivotally connected to an arm 41 which constitutes a part of the pawl or dog 16, said member being ivotally mounted upon a projecting bracket 42 which forms a part of the casing 11.

Assuming the various parts to occupy the positions shown, the operation of the device is as follows: Below the critical speed for which the device is adjusted to operate, the weighted member 4 and the members 5 and 6, which constitute a toggle between the member 4 and the body member 8, are maintained in their initial inner position, as hereinbefore set forth. If the speed of the shaft 3 increases to that for which the device is adjusted, the torque produced by the centrifugal force acting upon the weighted porclockwise direction, predominates over the torque which is effected through the agency of the spring 7 and tends to hold the arm 4 in its normal position. Hence, the resultant force on the weighted arm 4 causes said arm to be moved outwardly and, by reason of the peculiar arrangement of parts, the arm is thrown suddenly to its outer position after once being moved from its normal position. The reason for this positive action resides in the fact that the elongation of the spring 7 is relatively slight and, hence, when the weighted arm 4 once starts to move outwardly, the centrifugal force acting thereon increases more rapidly than the tension of the spring 7. Furthermore, as the arm 4 is moved outwardly, the lever arm through which the centrifugal force acts in producing a torque about the pivotal support 20 is decreased at a slower rate than the arm through which the spring 7 acts in opposition thereto. Furthermore, although there is no component force tending to rotate the arm 5 when the speed is normal, as soon as 0 any movement of the linkage mechanism is effected, the spring 7 is. slightly displaced in position toward the right, thus causing a slight force tending'to effect a clockwise rotation of the arm 5. This force tends to as- 1 5 sist the centrifugal force acting on the weighted portion 21 in throwing the weighted member 4 to its outer position. It is,

therefore, evident that no intermediate positained and that the member is thrown to its.

full outer position with a quick movement when the speed exceeds a predetermined value. Manifestly', when the weighted portion 21 occupies its full outer position, it delivers a positive blow to the pawl 16, thereby forcing the latch 15 to the left against theaction of the spring 38. In-so doing, the pin 35 is allowed to drop into the recess 37 and the movable contact member 13 is forced *downwardly into cooperative engagement with the stationary contact terminals 12 by means of the spring 14:. In order to reset the switching device 2, it is only necessary to push the rod 30 upwardly by means of the button 33, thereby raising the pin 35 out of engagement with the sides of the recess 37, after which the latch 15 is drawn to its extreme right position through the agency of the spring 38, in which position the supporting rod 30 and its associated movable contact member 13 are restrained.

Other structural features and arrangements and locations of parts may be employed within the spirit and scope of my invention, and I desire that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1. A centrifugal device comprising a r0 tatable member, a weightedarm pivotally connected thereto, a second arm pivotally connected to said rotatable member in substantially parallel relation to said weighted arm, a link connecting the free ends of said arms and a resilient means interposed between said link and a point on said rotatable member between the pivotal points of said arms to normallyrestrain the parts in their initial positions.

2. A-cen'trifugal device comprising a rotatable member, a weighted arm pivotally mounted thereon, a second arm pivotally connected to said rotatable member, a link. connecting said arms, and a resilient means interposed between said link and a point on said rotatable'member between the pivotal points of said arms for restraining said arms and link in their initial positions.

3. A centrifugal'device comprising 'a rotatable member, a weightedarm pivotally mounted thereon, a toggle connecting said arm to said member, and a spring interposed between 'a point on that member of said toggle which is connected to said weighted arm and an approximately opposite point on said rotatable member to prevent an outward movement of said weighted arm under predetermined speed conditions.

- 4. A centrifugal device comprising a ro tatable member, a pivotally mounted weighted arm'associated therewith, a toggle connecting said arm to said member, and a spring interposed between said toggle'and an approximately opposite point on said rotatable member to normally act in a direction substantially parallel to the toggle member that is directly attached to said rotatable member.

5. A centrifugal device comprising a rotatable member, a weighted arm pivotally mounted thereon, a second arm also pivotally connected to said member, a linkinterposed between, the free ends of said arm, and a spring connected to said rotatable member and to said link and disposed substantially parallel to said second arm for restraining said weighted arm in its initial position.

6; A centrifugal device comprising a r0- tatable member, a weighted arm pivotally mounted thereon and adapted to be moved outwardly by centrifugal force, a second arm pivotally mounted on said rotatable member, a link connecting the free ends of said arms and a spring interposed between an intermediate point in said link and an approximately opposite point on said rotata ble member to restralnthe weighted arm in its inner initial position under predetermined speed conditions and to permit it to be thrown outwardly with a quick movement when said conditions are exceeded.

7. A centrifugal device comprising a rotatable member, a pivotally mounted arm associated therewith and adapted to be moved outwardly by centrifugal force, and means comprising a second pivotally mounted arm, a link between said arms and a spring interposed between the link and the '100 rotatable member and disposed substantially parallel to the second arm to maintain the weighted arm in its initial position under normal speed conditions and to cause a quick outward movement thereof under abnormal speed conditions.

In testimony whereof, I have hereunto subscribed my name this 11th day of June 1912.

STANLEY L. ARMSTRONG.

Witnesses J. J. GANTNER, B. B. Hmns. 

